Effects of long-term paddy rice cultivation on soil arsenic speciation

Puu-Tai Yang; Yohey Hashimoto; Wen-Jing Wu; Jang-Hung Huang; Po-Neng Chiang; Shan-Li Wang

doi:10.1016/j.jenvman.2019.109768

Effects of long-term paddy rice cultivation on soil arsenic speciation

J Environ Manage. 2020 Jan 15:254:109768. doi: 10.1016/j.jenvman.2019.109768. Epub 2019 Nov 4.

Authors

Puu-Tai Yang¹, Yohey Hashimoto², Wen-Jing Wu³, Jang-Hung Huang³, Po-Neng Chiang⁴, Shan-Li Wang⁵

Affiliations

¹ Department of Agricultural Chemistry, National Taiwan University, Taipei, 10617, Taiwan.
² Department of Bioapplications and Systems Engineering, Tokyo University of Agriculture and Technology, Tokyo 184-8588, Japan.
³ Department of Soil and Environmental Sciences, National Chung Hsing University, Taichung, 40227, Taiwan.
⁴ Experimental Forest, National Taiwan University, Nantou, 55750, Taiwan.
⁵ Department of Agricultural Chemistry, National Taiwan University, Taipei, 10617, Taiwan. Electronic address: wangsl@ntu.edu.tw.

PMID: 31698298
DOI: 10.1016/j.jenvman.2019.109768

Abstract

Geochemical behavior of arsenic (As) in rice paddy soils determines the availability and mobility of As in the soils, but little is known about the long-term effects of paddy rice cultivation on As speciation in the soils. In this study, surface soil samples were collected from a rice paddy land and its adjacent dry land with similar soil properties and known cultivation histories. The soils of the paddy land and dry land contained 378 and 423 mg As kg^-1, respectively. The predominant As species in the soils were investigated using As K-edge X-ray absorption spectroscopy (XAS) in combination with two sequential chemical fractionation methods. The XAS results showed that the predominant As species in the soils were As(III)- and As(V)-ferrihydrite, As(V)-goethite and scorodite. In comparison to the dry land soil, the paddy land soil contained a higher proportion of As(V)-ferrihydrite and a lower proportion of scorodite. The results of chemical fractionation revealed that As in the paddy land soil was more labile than that in the dry land soil. It is therefore suggested that long-term rice cultivation enhances the mobility and availability of As in paddy soils.

Keywords: Arsenic speciation; Paddy soil; Redox transformation; Wet-dry cycles.

MeSH terms

Arsenic*
Oryza*
Soil
Soil Pollutants*
X-Ray Absorption Spectroscopy

Substances

Soil
Soil Pollutants
Arsenic